Electrical device for providing pain relief

ABSTRACT

An apparatus for relieving pain in a region of the body of a user by contacting electrodes to a surface of the body of the user at the region and providing a series of electrical impulses to the region, the apparatus including: (a) at least two electrodes adapted to contact a surface of a body of the user; (b) a control unit; and (c) a signal generator, associated with the control unit and responsive thereto, the signal generator and the control unit adapted to operative connect to a power supply, the signal generator adapted, in an operative mode, to provide a series of electrical impulses to the surface of the body, via the electrodes, the series including a plurality of cycles, each of the cycles having a positive voltage pulse and a negative voltage pulse, wherein a frequency of the plurality of cycles is optionally within a range of 60-150 cycles per second, wherein a time-averaged voltage amplitude (Va p ) of the positive voltage pulse, over an entire duration (Tp positive ) thereof, is 20-90 Volts, and wherein a ramp-up section of the positive voltage pulse fulfills at least one of the following structural conditions: (1) the positive voltage pulse attains at least 80% of the time-averaged voltage amplitude, within a time (T80) of 70-150 nanoseconds; (2) the positive voltage pulse increases by at least 20 Volts, within 70 nanoseconds.

RELATED APPLICATIONS

PCT/IB2017/054965 filed on Aug. 15, 2017 is incorporated herein byreference as if fully set forth herein.

FIELD OF THE INVENTION

The present invention relates to devices and methods for providing painrelief, and particularly to electrical devices and methods providingpain relief by providing electrical impulses to a surface of the body ata region at which pain is experienced.

SUMMARY OF THE INVENTION

According to some teachings of the present invention there is provided anon-invasive device for providing pain relief to a human user, thedevice including: (a) at least two electrodes adapted to contact asurface of a body of the user; (b) a control unit; and (c) a signalgenerator, associated with the control unit and responsive thereto, thesignal generator and the control unit adapted to operative connect to apower supply, the signal generator adapted, in an operative mode, toprovide a series of electrical impulses to the surface of the body, viathe electrodes, the series including a plurality of cycles, each of thecycles having a positive voltage pulse and a negative voltage pulse,wherein a frequency of the plurality of cycles is optionally within arange of 60-150 cycles per second, wherein a time-averaged voltageamplitude (Va_(p)) of the positive voltage pulse, over an entireduration (Tp_(positive)) thereof, is 20-90 Volts, and wherein a ramp-upsection of the positive voltage pulse fulfills at least one of thefollowing structural conditions: (1) the positive voltage pulse attainsat least 80% of the time-averaged voltage amplitude, within a time (T80)of 70-150 nanoseconds; (2) the positive voltage pulse increases by atleast 20 Volts, within 70 nanoseconds.

According to further teachings of the present invention there isprovided a non-invasive device for providing pain relief to a humanuser, the device including: (a) at least two electrodes adapted tocontact a surface of a body of the user; (b) a control unit; and (c) asignal generator, associated with the control unit and responsivethereto, the signal generator and the control unit adapted to operativeconnect to a power supply, the signal generator adapted, in an operativemode, to provide a series of electrical impulses to the surface of thebody, via the electrodes, the series including a plurality of cycles,each of the cycles having a positive voltage pulse and a negativevoltage pulse, wherein a time-averaged voltage amplitude (Va_(p)) of thepositive voltage pulse, over an entire duration (Tp_(positive)) thereof,is 20-90 Volts, wherein a ramp-up section of a the positive voltagepulse of cycles in a first subset of the plurality of cycles has a firstramp up time, a ramp-up section of a the positive voltage pulse ofcycles in a second subset of the plurality of cycles, following thefirst subset, has a second ramp up time, shorter than the first ramp uptime, and wherein the ramp-up section of the positive voltage pulse ofthe cycles in the second subset fulfills at least one of the followingstructural conditions: (1) the positive voltage pulse attains at least80% of the time-averaged voltage amplitude, within a time (T80) of70-150 nanoseconds; (2) the positive voltage pulse increases by at least20 Volts, within 70 nanoseconds.

According to further teachings of the present invention there isprovided a method for providing pain relief to a user, the methodincluding: (a) providing a device as described herein; (b) attaching theat least two electrodes to the surface of the body of the user; and (c)activating the signal generator to operate in the operative mode toprovide the series of electrical impulses to the surface of the body,via the electrodes.

According to further features in the described preferred embodiments,the attaching includes attaching the at least two electrodes to thesurface of the body at a region at which pain is felt by the user.

According to still further features in the described preferredembodiments, the region at which pain is felt by the user is anabdominal area of the user.

According to still further features in the described preferredembodiments, the method is effected so as to provide relief to menstrualor pre-menstrual pains.

According to still further features in the described preferredembodiments, the method further includes the user wearing the device.

According to still further features in the described preferredembodiments, the wearing includes attaching the device to a garment wornby the user.

According to still further features in the described preferredembodiments, the wearing includes wearing the device while the device isin the operative mode.

According to still further features in the described preferredembodiments, the device is portable, the method further including theuser moving a distance of at least ten, at least five, or at least threemeters while wearing the device, in the operative mode, for at least 10,at least 5, or at least 3 minutes.

According to still further features in the described preferredembodiments, T80 is at least 75 nanoseconds.

According to still further features in the described preferredembodiments, T80 is at least 80 nanoseconds.

According to still further features in the described preferredembodiments, T80 is at most 140 nanoseconds.

According to still further features in the described preferredembodiments, T80 is at most 130 nanoseconds.

According to still further features in the described preferredembodiments, T80 is at most 120 nanoseconds.

According to still further features in the described preferredembodiments, T80 is at most 115 nanoseconds.

According to still further features in the described preferredembodiments, T80 is at most 110 nanoseconds.

According to still further features in the described preferredembodiments, the positive voltage pulse increases by at least 20 Volts,within 70 nanoseconds.

According to still further features in the described preferredembodiments, the positive voltage pulse increases by at least 30 Volts,within 70 nanoseconds.

According to still further features in the described preferredembodiments, the positive voltage pulse increases by at least 40 Volts,within 70 nanoseconds.

According to still further features in the described preferredembodiments, the positive voltage pulse increases by at least 50 Volts,within 70 nanoseconds.

According to still further features in the described preferredembodiments, an intermediate time (Ti) between the positive voltagepulse and the negative voltage pulse is at least 0.1 milliseconds, atleast 0.2 milliseconds, at least 0.3 milliseconds, or at least 0.4milliseconds.

According to still further features in the described preferredembodiments, the intermediate time (Ti) is at most 1 millisecond, atmost 0.9 milliseconds, at most 0.8 milliseconds, or at most 0.7milliseconds.

According to still further features in the described preferredembodiments, the positive pulse attains at least 80% of thetime-averaged voltage amplitude for a pulse duration within a range of70-130 microseconds, 80-120 microseconds, or 90-110 microseconds.

According to still further features in the described preferredembodiments, the positive pulse has a substantially constant voltageamplitude for a pulse duration within a range of 70-130 microseconds,80-120 microseconds, or 90-110 microseconds.

According to still further features in the described preferredembodiments, the frequency of the plurality of cycles is within a rangeof 70-140 cycles per second, 80-130 cycles per second, or 80-120 cyclesper second.

According to still further features in the described preferredembodiments, the negative voltage pulse is area-symmetric with respectto the positive voltage pulse, within 10 area %, within 5 area %, within2 area %, or within 1 area %.

According to still further features in the described preferredembodiments, the positive voltage pulse attains at least 80%, at least85%, at least 90%, at least 95%, or substantially 100% of thetime-averaged voltage amplitude, within 70-150 nanoseconds.

According to still further features in the described preferredembodiments, the signal generator includes a low voltage signalgenerator adapted to produce a low voltage AC signal, the low voltagesignal generator producing a peak voltage of up to 10.0 volts up to 5.0volts.

According to still further features in the described preferredembodiments, the signal generator includes at least one of a voltagepre-amplifier and a voltage amplifier, adapted to amplify the voltage ofa signal provided as input thereto.

According to still further features in the described preferredembodiments, the voltage pre-amplifier and/or the voltage amplifier isdisposed electrically downstream with respect to a low voltage signalgenerator, and receives as input a the low voltage AC signal generatedby the low voltage signal generator.

According to still further features in the described preferredembodiments, the signal generator includes a transformer adapted toamplify the voltage of a signal provided as input thereto.

According to still further features in the described preferredembodiments, the transformer is disposed electrically downstream withrespect to the voltage pre-amplifier and the voltage amplifier.

According to still further features in the described preferredembodiments, the signal generator includes an AC-to-DC converterdisposed electrically downstream relative to the transformer and adaptedto produce a substantially DC signal from an input signal providedthereto.

According to still further features in the described preferredembodiments, the signal generator includes an AC-to-DC converter adaptedto produce a substantially DC signal.

According to still further features in the described preferredembodiments, the AC-to-DC converter is disposed electrically downstreamwith respect to the voltage pre-amplifier and the voltage amplifier.

According to still further features in the described preferredembodiments, the AC-to-DC converter includes a diode circuit adapted toproduce the substantially DC signal.

According to still further features in the described preferredembodiments, the diode circuit includes at least one diode, and acapacitor disposed electrically downstream of the at least one diode.

According to still further features in the described preferredembodiments, the signal generator includes a switching mechanism,responsive to the control unit, adapted to transform an input signalprovided to the switching mechanism into the series of electricalimpulses.

According to still further features in the described preferredembodiments, the switching mechanism receives as the input signal asubstantially DC signal.

According to still further features in the described preferredembodiments, the switching mechanism includes a first switch, responsiveto the control unit, adapted to generate from the substantially DCsignal the positive voltage pulses of the series, and a second switch,responsive to the control unit, adapted to generate from thesubstantially DC signal the negative voltage pulses of the series.

According to still further features in the described preferredembodiments, the power supply includes a low voltage power supplyadapted to provide a nominal voltage of at most 10 volts, at most 8.0volts, at most 6.0 volts, at most 5.0 volts, at most 4.0 volts, or atmost 3.0 volts.

According to still further features in the described preferredembodiments, the device further includes a housing enclosing the controlunit, the signal generator, and the power supply.

According to still further features in the described preferredembodiments, in the operative mode, the power supply enclosed in thehousing is the sole power supply for the device.

According to still further features in the described preferredembodiments, the housing has dimensions within the range of 4 cm×4 cm×8mm to 6 cm×6 cm×13 mm.

According to still further features in the described preferredembodiments, the device has a weight in the range of 90 to 150 grams,excluding any power supply enclosed in the housing.

According to still further features in the described preferredembodiments, the device is portable while in the operative mode.

According to still further features in the described preferredembodiments, the electrodes are adapted to contact the surface of thebody of the user at a region of the body at which pain is experienced.

According to still further features in the described preferredembodiments, a ramp-up section of a positive voltage pulse of cycles ina third subset of the plurality of cycles, following the second subset,has a third ramp up time, which is shorter than the second ramp up time.

According to still further features in the described preferredembodiments, a time-averaged voltage amplitude (Va_(n)) of the negativevoltage pulse, over an entire duration (Tp_(negative)) thereof, is 20-90Volts.

According to still further features in the described preferredembodiments, a ramp-up section of the negative voltage pulse fulfills atleast one of the following structural conditions: (1) the negativevoltage pulse attains at least 80% of the time-averaged voltageamplitude, within a time (T80) of 70-150 nanoseconds; (2) the negativevoltage pulse decreases by at least 20 Volts, within 70 nanoseconds.

According to still further features in the described preferredembodiments, the ramp-up section of the negative voltage pulse decreasesby at least 20 Volts, at least 30 Volts, at least 30 Volts, or at least50 Volts, within 70 nanoseconds.

According to still further features in the described preferredembodiments, the negative pulse attains at least 80% of thetime-averaged voltage amplitude for a pulse duration within a range of70-130 microseconds, 80-120 microseconds, or 90-110 microseconds.

According to still further features in the described preferredembodiments, the negative pulse has a substantially constant voltageamplitude for a pulse duration within a range of 70-130 microseconds,80-120 microseconds, or 90-110 microseconds.

According to still further features in the described preferredembodiments, the negative voltage pulse attains at least 80%, at least85%, at least 90%, at least 95%, or substantially 100% of thetime-averaged voltage amplitude, within 70-150 nanoseconds.

BRIEF DESCRIPTION OF THE FIGURES

The invention is herein described, by way of example only, withreference to the accompanying drawings. With specific reference now tothe drawings in detail, it is stressed that the particulars shown are byway of example and for purposes of illustrative discussion of thepreferred embodiments of the present invention only, and are presentedin the cause of providing what is believed to be the most useful andreadily understood description of the principles and conceptual aspectsof the invention. In this regard, no attempt is made to show structuraldetails of the invention in more detail than is necessary for afundamental understanding of the invention, the description taken withthe drawings making apparent to those skilled in the art how the severalforms of the invention may be embodied in practice. Throughout thedrawings, like-referenced characters are used to designate likefunctionalities, but not necessarily identical elements.

In the drawings:

FIG. 1 is a schematic block diagram of an embodiment of an inventivedevice for providing pain relief utilizing an inventive series ofelectrical impulses, according to an embodiment of the teachings herein;

FIG. 2 is a schematic block diagram of a signal generator according toan embodiment of the teachings herein, the signal generator forming partof the device of FIG. 1 ;

FIG. 3 is a simplified electrical chart of a transformer and an AC-to-DCsignal converter according to the teachings herein, the transformer andAC-to-DC signal converter forming part of the signal generator of FIG. 2;

FIGS. 4A-4F are schematic illustrations of pulses transmitted fromdifferent components of the signal generator of FIG. 2 in accordancewith an embodiment of the teachings herein;

FIG. 5A is a schematic illustration of an electrical signal transmittedby prior art devices for relief of pain;

FIG. 5B is a schematic illustration of an inventive electrical signalaccording to the teachings herein, which may be generated by the signalgenerator of FIG. 2 ; and

FIG. 6 is a schematic illustration of a series of electrical signalsaccording to an embodiment of the teachings herein.

DETAILED DESCRIPTION

Systems and methods are described herein that apply electrical impulsesto the surface of the body of a user at a region of the body at whichpain is experienced, thereby to relieve the pain.

Reference is now made to FIG. 1 , which is a schematic block diagram ofan embodiment of an inventive device for providing pain relief utilizingan inventive series of electrical impulses according to an embodiment ofthe teachings herein.

As seen, a device 100 for providing pain relief may include at least twostimulating electrodes 102, which are functionally associated with asignal generator 104. The electrodes 102 receive from signal generator104 an electrical signal to be provided to the surface of the skin ofthe user. The stimulating electrodes 102 are adapted to contact asurface of the body of the user at a region of the body at which pain isexperienced, and, in an operative mode, to deliver electrical impulsesto the surface of the body as described hereinbelow.

The signal generator 104 is functionally associated with, and receivesinstructions from, a control unit 106, which may, in some embodiments,be functionally associated with an input module 108 for providing inputto the control unit 106, and with an output module 110 via which controlunit 106 provides an output to the user. The control unit may be anysuitable control unit, such as an 8/16 bit AVR® XMEGA® microcontrollercommercially available from Atmel® of San Jose, California, USA.

In some embodiments, the input module 108 includes, or may be associatedwith, a user interface 109 including an on/off switch for activatingand/or terminating activation of the device 100.

In some embodiments, user interface 109 includes one or more adjustmentbuttons or settings for increasing and decreasing the desired peakvoltage.

In some embodiments, the signal generator 104, control unit 106, inputmodule 108, and output module 110 may be electrically associated withand powered by one or more power supplies 112. In some embodiments, thepower supply 112 is a low voltage power supply, providing a nominalvoltage of at most 10.0 volts, at most 8.0 volts, at most 6.0 volts, atmost 5.0 volts, at most 4.0 volts, or at most 3.0 volts. In someembodiments, the power supply includes at least one rechargeablebattery, such as at least one nickel-metal hydride (NiMH) battery,nickel-cadmium (NiCd) battery, lithium-ion (Li-ion) battery, or lithiumpolymer (Li-Poly) battery. In some embodiments, the device 100 ispowered solely by power provided by the rechargeable battery, and doesnot require connection to an additional power supply for functioningthereof when the rechargeable battery is sufficiently charged.

The signal generator 104, control unit 106, and power supply 112 may beenclosed in a housing 120, which may include a port 122 for connectionof the electrodes 102 to the signal generator 104, and/or a port 124 forconnection of the power supply 112 to an external power source, forexample for connection of a charging cable connected to an electricalsocket.

In some embodiments, the device has dimensions within the range of 4cm×4 cm×8 mm to 6 cm×6 cm×13 mm, and more typically, within the range of4 cm×4 cm×9 mm to 5.3 cm×5.3 cm×12 mm. The weight of the device,excluding the battery, is 90 to 150 grams, and more typically, 100 to125 grams.

In some embodiments, the device 100 may be readily be worn by the user,for example clipped onto a garment thereof. In some embodiments, thedevice 100 is portable, and can function in its operative signalproviding mode while being transported, or moved, from one place toanother, or while the user is in motion.

Reference is now additionally made to FIG. 2 , which is a schematicblock diagram of signal generator 104 of device 100 according to anembodiment of the teachings herein.

Signal generator 104 may optionally include a signal generator such as alow voltage signal generator 200, which generates an alternating current(AC) signal 400 as shown in FIG. 4A. In some embodiments, the signalgenerated by low voltage signal generator 200 has a peak voltage withinthe range of 3.0-10.0 volts, and more typically, within the range of3.0-5.0 volts.

In some embodiments, the signal 400 generated by low voltage signalgenerator 200 may be provided to a voltage pre-amplifier 202. Thevoltage pre-amplifier 202 increases the voltage of the received signal,to generate a new AC signal 402 having a higher voltage, as shown inFIG. 4B. In some embodiments, the voltage pre-amplifier 202 may bereplaced by a voltage amplifier having similar functionality.

In some embodiments, power supply 112 (shown in FIG. 1 ) can deliver avoltage directly to any one of components 200, 202, 204, or 206.

In some embodiments, power supply 112 can deliver a high DC voltage(e.g., at least 20 volts) directly to switching mechanism 210.

The signal 402 output by pre-amplifier 202 is provided to a transformer204, such as an LPR6235 transformer commercially available fromCoilcraft® Inc. of Cary, Illinois, USA. At the expense of reducedcurrent output, transformer 204 increases the voltage of the receivedsignal, to generate a new AC signal 404 having a higher voltage thansignal 402, as seen in FIG. 4C.

The signal 404 output by transformer 204 is provided to an AC-to-DCconverter 206. In some embodiments, such as the embodiment illustratedin FIG. 3 , the AC-to-DC converter 206 includes a diode circuit 300including at least one diode 302 and a capacitor 304 disposed downstreamthereto. Signal 404 output by the transformer 204 is provided as inputto the diode 302, which selects from the signal 404 the positive voltagesegments, resulting in the signal 406 illustrated in FIG. 4D. It isappreciated that the negative voltage segments may be obtained fromsignal 404 by reversing the direction of diode 302, as is known in theart.

The signal 406 generated by the diode 302, and in some embodiments alsothe corresponding signal generated by the reversed diode 302, isprovided as input to the capacitor 304, which converts the signal into aDC signal 408 having a fixed voltage, as illustrated in FIG. 4E.

The DC signal 408 output by capacitor 304 is provided as input to aswitching mechanism 210, such as a BSS123LT1G or a BVSS123LT1Gcommercially available from ON Semiconductor® of Phoenix, Arizona, USA.

In some embodiments, the switching mechanism includes a first switch 212a generating a positive pulse of the generated signal, and a secondswitch 212 b generating a negative pulse of the generated signal, asdescribed in further detail hereinbelow. Switching mechanism 210, and insome embodiments, each of switches 212 a and 212 b, may be controlled bycontrol unit 106 to produce signal 410, illustrated in FIG. 4F. Signal410 is provided to the electrodes 102 and therefrom to the surface ofthe user's body. Signal 410 and characteristics thereof are described infurther detail hereinbelow with respect to FIG. 5B.

Reference is additionally made to FIG. 5A, which is a schematicillustration of an electrical signal transmitted by prior art devicesfor relief of pain, and to FIG. 5B, which is a schematic illustration ofan inventive electrical signal according to the teachings herein, whichmay be generator by the signal generator of FIG. 2 . It will beappreciated that the signals in FIGS. 5A and 5B are not drawn to scale,and are not intended to limit the durations of different portions of thesignals, only to provide an understanding of the structures and shapesof these signals.

As seen in FIGS. 5A, prior art devices for relief of pain provide asignal 500 defining a pulse 502. Pulse 502 has a total pulse time (Tp),which includes: (a) a ramp-up time (Tru), indicated by segment 505 ofthe pulse, (b) a peak-voltage time (Tpv), indicated by segment 506 ofthe pulse, and (c) a ramp down time (Trd), indicated by segment 508 ofthe pulse.

The peak voltage is defined as a voltage within 15%, within 10%, within5%, within 3%, or within 1% of the maximal voltage in the pulse. Themaximal voltage in the pulse is the highest voltage attained by apositive voltage pulse, or the lowest voltage attained by a negativevoltage pulse, during the entire duration of the pulse.

The ramp-up time (Tru) is generally the time in which the voltage of thepulse increases, or transitions, to at least 80%, at least 85%, at least90%, at least 95%, or substantially 100% of the peak voltage or of themaximal voltage of the signal. Typically, the ramp up time includes anincrease in voltage from a baseline voltage, which is typically zero.Conversely, the ramp-down time (Trd) is generally the time in which thevoltage of the pulse decreases, or transitions, from the peak voltage ofmaximal voltage for the signal by at least 80%, at least 85%, at least90%, at least 95%, or at substantially 100% of the voltage, or to avoltage that is at most 20%, at most 15%, at most 10%, at most 5%, orsubstantially equal to the baseline voltage, typically zero.

The ramp-up time Tru of prior art devices may be at least 0.5microseconds, and more typically, in the range of 0.5-1 microseconds(500-1000 nanoseconds).

Turning to FIG. 5B, it is seen that a signal 550 provided by theinventive device 100 of FIGS. 1-3 includes multiple cycles, each cyclebeing bi-phasic and including a positive voltage pulse 552 having apositive voltage and a negative voltage pulse 554 having a negativevoltage. Each of positive voltage pulse 552 and negative voltage pulse554 has a total pulse time (Tp) (indicated as Tp_(positive) for thepositive voltage pulse 552 and as Tp_(negative) for the negative voltagepulse 554), which includes a ramp-up time (Tru), a peak-voltage time(Tpv), and a ramp down time (Trd). For each of the positive and negativevoltage pulses 552 and 554, a ramp up segment of the pulse is indicatedby reference numeral 556, a ramp down segment of the pulse is indicatedby reference numeral 558, and a peak voltage segment of the pulse isindicated by reference numeral 555. It will be appreciated that theramp-up segment 556 of the positive voltage signal 552 is achieved bythe control unit 106 operating switch 212 a. The ramp down segment 558may be provided passively, by the switch 212 a or switching mechanism210 stopping operation to provide a signal, or may alternately beprovided actively, by the switch 212 a actively lowering the voltageprovided by pulse 552.

Similarly, it will be appreciated that the ramp-up segment 556 of thenegative voltage signal 554 is provided by the control unit 106operating switch 212 b. The ramp down segment 558 may be providedpassively, by the switch 212 b or switching mechanism 210 stoppingoperation to provide a signal, or may alternately be provided beprovided actively, by the switch 212 b actively increasing the voltageprovided by pulse 554.

In some embodiments, the positive voltage pulse 552 has a time-averagedvoltage amplitude (Va_(p)), over the entire duration (Tp_(positive))thereof, in the range of 20-90 Volts, and the negative voltage pulse 554has a time-averaged voltage amplitude (Va_(n)), over the entire duration(Tp_(negative)) thereof, in the range of −20-−90 Volts.

The ramp up time (Tru) and ramp down time (Trd) are defined as discussedhereinabove with respect to FIG. 5A. It will be appreciated by people ofskill in the art that in the positive voltage pulse 552, the peakvoltage is a positive voltage, and as such during the ramp up time thevoltage increases from the baseline voltage, typically zero, towards thepeak voltage, and during the ramp down time the voltage decreases fromthe peak voltage towards the baseline voltage, whereas in the negativevoltage pulse 554 the peak voltage is a negative voltage, and as suchduring the ramp up time the voltage decreases from the baseline voltagetowards the peak voltage, and during the ramp down time the voltageincreases from the peak voltage back towards the baseline voltage.

Specifically, it is a particular feature of the teachings herein thatthe positive voltage pulse 552 attains at least 80% of the time-averagedvoltage amplitude (Va_(p)) within a time (T80) of 70-150 nanoseconds,and/or that the positive voltage pulse 552 increases by at least 20Volts within 70 nanoseconds. Similarly, the negative voltage pulse 554attains at least 80% of the negative time-averaged voltage amplitude(Va_(n)) within a time (T80) of 70-150 nanoseconds, and/or decreases byat least 20 Volts within 70 nanoseconds.

In some embodiments, T(80) is at least 75 nanoseconds or at least 80nanoseconds. In some embodiments, T(80) is at most 140 nanoseconds, atmost 130 nanoseconds, at most 120 nanoseconds, at most 115 nanoseconds,or at most 110 nanoseconds.

In some embodiments, the positive voltage pulse 552 increases by atleast 30 Volts, by at least 40 Volts, or by at least 50 Volts, within 70nanoseconds. In some embodiments, the negative voltage pulse 554decreases by at least 30 Volts, by at least 40 Volts, or by at least 50Volts, within 70 nanoseconds.

In some embodiments, the positive voltage pulse 552 attains at least80%, at least 85%, at least 90%, at least 95%, or substantially 100% ofthe time-averaged voltage amplitude (Va_(p)) within 70-150 nanoseconds,75-140 nanoseconds, 80-130 nanoseconds, 80-120 nanoseconds, or 80-110nanoseconds.

In some embodiments, the negative voltage pulse 554 attains at least80%, at least 85%, at least 90%, at least 95%, or substantially 100% ofthe time-averaged voltage amplitude (Va_(n)) within 70-150 nanoseconds,75-140 nanoseconds, 80-130 nanoseconds, 80-120 nanoseconds, or 80-110nanoseconds.

As such, in some embodiments, the ramp-up time (Tru), which iscontrolled by switching mechanism 210, is in the range of 50-200nanoseconds, 60-175 nanoseconds, 70-150 nanoseconds, 75-140 nanoseconds,80-130 nanoseconds, 80-120 nanoseconds, or 80-110 nanoseconds.

As is clearly understood from comparison of FIGS. 5A and 5B, the ramp-uptime (Tru) during which the prior art pulse 502 ramps up to reach thepeak voltage, is significantly longer than the ramp-up time during whichthe positive voltage pulse 552 of the present invention reaches the peakvoltage. The inventor has surprisingly discovered that the short ramp-uptime is associated with improved alleviation of pain and discomfort,including alleviation of physiological pain and/or of instrumentallyinduced pain, if such exists.

More specifically, the inventor has found that at a ramp-up time of lessthan 70 ns, the instrumentally-induced pain greatly increases, and isnot sufficiently compensated for by the pain-relief mechanisms of thebody. The inventor has further found that at ramp-up times in excess of200 ns, the instrumentally induced pain may be greatly reduced, butactivation of the pain-relief mechanisms of the body (e.g., generationof opiates or morphine-like substances) is also greatly reduced, suchthat such slow ramp-up times are relatively inefficacious in alleviatingthe pain of the user.

Without wishing to be bound by theory, Applicants believe that the rapidramp up of the signal provided by the present invention at the region ofthe body at which pain is felt by the user, causes the brain to send tothat region a significantly increased amount of opiates or morphine-likemolecules, which provide rapid and effective pain relief to the area,and which also provide immediate and substantially complete relief toany pain experienced by the user due to provision of the signal, suchthat the signal does not, in and of itself, cause the user pain, and theenhanced presence of opiates or morphine-like molecules in that area ofthe body relieve the previously felt pain for which the user isreceiving treatment.

Stated differently, Applicants believe that the provision of theelectrical signals to the area at which the pain is felt, occupies thepain feeling neurons in the area, resulting in the brain providing painrelieving molecules to the area in a quantity which is sufficient foreffectively eliminating the pain felt by the provision of the signal, ifany, and for relieving the pain for which treatment is being sought. Anintermediate time (Ti), is defined as the time between the positivevoltage pulse 552 and the negative voltage pulse 554, and a rest time(Trest), is defined as the rest time between cycles, or as the time fromthe end of the negative voltage pulse 554 of one cycle and the beginningof the positive voltage pulse 552 of the next cycle. The total time foreach cycle (Ttotal) is defined asTtotal=Tp_(positive)+Tp_(negative)+Ti+Trest.

In some embodiments, the frequency of the cycles in signal 550 is in therange of 60-150 cycles per second, 70-140 cycles per second, 80-130cycles per second, or 80-120 cycles per second. Stated differently, thetotal time (Ttotal) for each cycle is in the range of 6.5-16.7milliseconds, in the range of 7.1-14.3 milliseconds, in the range of7.7-12.5 milliseconds, or in the range of 8.3-12.5 milliseconds.

In some embodiments, the total pulse time (Tp) for each of the positiveand negative voltage pulses 552 and 554 is in the range of 70-130microseconds, in the range of 80-120 microseconds, or in the range of90-110 microseconds. In some embodiments, the positive pulse attains atleast 80% of Va_(p), and/or the negative pulse attains at least 80% ofVa_(n), for a pulse duration within the range of 70-130 microseconds, inthe range of 80-120 microseconds, or in the range of 90-110microseconds. In some embodiments, the positive voltage pulse and/or thenegative voltage pulse has a substantially constant voltage amplitudefor a pulse duration within a range of 70-130 microseconds, 80-120microseconds, or 90-110 microseconds.

In some embodiments, the intermediate time (Ti) for each cycle is atleast 0.1 millisecond, at least 0.2 milliseconds, at least 0.3milliseconds, or at least 0.4 milliseconds. In some embodiments, theintermediate time (Ti) for each cycle is at most 1 millisecond, at most0.9 milliseconds, at most 0.8 milliseconds, or at most 0.7 milliseconds.

In some embodiments, the rest time (Trest) between the end of a finalvoltage impulse of a particular cycle, and the beginning of an initialvoltage impulse of a subsequent, adjacent particular cycle is at least0.3 milliseconds, at least 0.4 milliseconds, or at least 0.5milliseconds. In some embodiments, Trest for each cycle is at most 1millisecond, at most 0.9 milliseconds, at most 0.8 milliseconds, or atmost 0.7 milliseconds.

In some embodiments, the negative voltage pulse 554 is area-symmetricwith respect to the positive voltage pulse 552, within 10 area %, within5 area %, within 2 area %, or within 1 area %. Stated differently, thecumulative charge provided by the negative voltage pulse 554 to thesurface of the body of the user is within 10%, 5%, 2%, or 1% of thecumulative charge provided by the positive voltage pulse 552 to thesurface of the body of the user. As such, in some embodiments, eachcycle in the signal 550 is a balanced bi-phasic cycle.

Reference is now made to FIG. 6 , which is a schematic illustration of aseries of electrical signals according to an embodiment of the teachingsherein. As shown, an electrical signal 600 includes a plurality ofcycles 602, each including a positive voltage pulse 604 having a similarstructure to that of positive voltage pulse 552 of FIG. 5B and anegative voltage pulse 606 having a similar structure to that ofnegative voltage pulse 554 of FIG. 5B.

In each cycle 602, the ramp-up time (Tru) of the positive voltage pulseis substantially equal to the ramp up time of the negative voltagepulse, but the ramp up times are different between cycles. Morespecifically, with each cycle 602 the ramp up time Tru decreases orgradually decreases, until the ramp-up time of 70-150 nanoseconds,described in detail with respect to FIG. 5B, is reached.

As such, in the first cycle 602 a, or in a first sequence of suchcycles, the positive and negative voltage pulses have a relatively longramp up time, which may, in some embodiments, be greater than 100nanoseconds, or in the range of 100-200 nanoseconds. In subsequentcycles, or sequences of cycles, the positive and negative voltage pulseshave increasingly shorter ramp-up times. For example, the second cycle602 b, or second sequence of cycles, may have a ramp-up time of 100nanoseconds, the third cycle 602 c, or third sequence of cycles, mayhave a ramp up time of 95 or 90 nanoseconds, and so on, until the rampup time reaches the desired ramp-up time, for example 80 nanoseconds,shown in the two last illustrated cycles, 602 e and 602 f. It will beappreciated that in accordance with the teachings herein, any additionalcycles following cycle 602 f will continue to have a ramp-up time in therange of 70-150 nanoseconds, as described hereinabove.

Without wishing to be bound by theory, the inventor believe that thesignal shown in FIG. 6 would eliminate any residual pain caused byprovision of the signal, in that such pain would not be generated due tothe relatively long ramp-up time of the first cycle 602 a, and that thatthe pulses provided in cycle 602 a would cause the body to deliver tothe region at which the electrodes are placed sufficient pain relievingmolecules, such as opiates or morphine-like molecules, to relieve anypain felt by the somewhat shorter ramp up time of the pulses in signal602 b. The inventor believes that this behavior would continue andsufficient pain relieving molecules would be present at the beginning ofeach cycle, other than cycle 602 a, such that no pain would be felt bythe user due to the provision of the signal—in cycle 602 a because theramp up time is sufficiently long so as not to cause pain as is known inthe art, and in the following cycles because sufficient pain relievingmolecules will have been delivered to the vicinity of the electrodes andwould alleviate any pain potentially caused by the provision of thesignals.

A device such as the devices described in conjunction with any of FIGS.1-3 may be provided to a user. In typical use, the user or clinicianattaches the electrodes 102 to a surface of the body, in a general areawhere pain is experienced. In some embodiments, the pain is a menstrualor pre-menstrual pain, and the user attaches the electrodes to the skinsurface at or near an abdominal region of the body, where the pain isexperienced.

Once the electrodes are attached to the skin of the user, the user usesthe user interface 109 to activate the device 100, such processor 106activates signal generator 104 to provide signals as described in FIG.5B to the skin surface of the user's body, thereby to relieve the pain.In some embodiments, the user may then provide input to processor 106via input module 108 and/or user interface 109 thereof, for example toindicate whether the treatment is helping, to increase or decrease thefrequency or intensity of the signals, or to terminate activity ofdevice 100.

In some embodiments, the user may wear the device, before, after, andduring operation thereof, for example clipped to a garment worn by theuser. In such embodiments, the device 100 is portable, and as such maybe used in the operative mode, while worn by the user and/or solelyusing the on-board power supply, when the user is moving around, withoutbeing tied to a specific location, for a duration of at least 5 minutes,at least 10 minutes, at least 15 minutes, or at least 30 minutes.

As used herein in the specification and in the claims section thatfollows, the term “or” is considered as inclusive, and therefore thephrase “A or B” means any of the groups “A”, “B”, and “A and B”.

As used herein in the specification and in the claims section thatfollows, the terms “pulse”, “signal”, and “impulse” all relate to anelectrical signal, for example applied via an electrode.

As used herein in the specification and in the claims section thatfollows, the term “cycle” relates to a repetitive or semi-repetitivebi-phasic segment of an electrical voltage signal, as is generallyrecognized and understood in the art. Represented on a voltage vs. timeplot, a “cycle” typically consists of a positive voltage pulse, anegative voltage pulse, any intermediate time (Ti) therebetween, and therest time (Trest) between the end of a final voltage impulse of aparticular cycle, and the beginning of an initial voltage impulse of asubsequent, adjacent particular cycle. As a matter of convention,Trest≥Ti.

As used herein in the specification and in the claims section thatfollows, the term “positive voltage pulse” relates to an electricalpulse providing an electrical signal having positive voltage, whether anabsolute positive voltage or a positive voltage relative to a baselinevoltage. Typically the baseline voltage is zero.

As used herein in the specification and in the claims section thatfollows, the term “negative voltage pulse” relates to an electricalpulse providing an electrical signal having negative voltage, whether anabsolute negative voltage or a negative voltage relative to a baselinevoltage. Typically the baseline voltage is zero.

As used herein in the specification and in the claims section thatfollows, the term “peak voltage” relates to a voltage within 15%, within10%, within 5%, within 3%, or within 1% of the maximal voltage in thepulse. The peak voltage of a positive voltage pulse is a positivevoltage and the peak voltage of a negative voltage pulse is a negativevoltage.

As used herein in the specification and in the claims section thatfollows, the term “peak voltage time” relates to the duration in whichthe pulse attains the peak voltage.

As used herein in the specification and in the claims section thatfollows, the term “maximal voltage” relates to the highest voltageattained by a positive voltage pulse, or the lowest voltage attained bya negative voltage pulse, during the entire duration of the pulse. Asused herein in the specification and in the claims section that follows,the term “ramp-up time” relates to the time in which the voltage of thepulse, or the absolute value or magnitude of the voltage of the pulse,increases to at least 80%, at least 85%, at least 90%, at least 95%, orsubstantially 100%, of the peak voltage.

As used herein in the specification and in the claims section thatfollows, the term “ramp-down time” relates to the time in which thevoltage of the pulse, or the absolute value or magnitude of the voltageof the pulse, decreases by at least 80%, at least 85%, at least 90%, atleast 95%, or substantially 100%, of the peak voltage, or to be within20%, within 15%, within 10%, within 5%, or substantially equal to, thebaseline voltage.

As used herein in the specification and in the claims section thatfollows, the term “timed-averaged voltage amplitude” relates to theaverage voltage amplitude over a predetermined time duration, forexample the average voltage amplitude for a positive or negative voltagepulse over the entire duration thereof, or over a segment of thepositive or negative voltage pulse at which a peak voltage amplitude isattained. Due to the extremely swift ramp-up times utilized in thepresent invention, the “timed-averaged voltage amplitude” of the“plateau” of such a pulse may be approximated by the “timed-averagedvoltage amplitude” of the pulse, or the “timed-averaged voltageamplitude” of the portion of the pulse in which voltage is applied,e.g., taken over the ramp-up time (Tru) and the peak-voltage time (Tpv).

As used herein in the specification and in the claims section thatfollows, the term “substantially constant voltage amplitude”, withregard to a voltage pulse, or a portion thereof, relates to a voltageamplitude being constant, within a deviation of 15%, 10%, 5%, 3%, or 1%.

As used herein in the specification and in the claims section thatfollows, the term “area-symmetric” relates to two voltage pulses, suchas a positive voltage pulse and a negative voltage pulse, which, when anamplitude thereof is plotted relative to time and relative to a baselinevoltage or relative to a zero voltage, the areas trapped between theplots of the two pulses' amplitudes and of the baseline voltage areequal, or are within 10%, within 5%, within 2%, within 1%, of oneanother.

As used herein in the specification and in the claims section thatfollows, the term “balanced cycle” relates to a cycle including apositive voltage pulse and a negative voltage pulse, such that thecharge provided by the positive and negative voltage signals is equal,or is within 15%, within 10%, within 5%, within 3%, or within 1% of oneanother.

As used herein in the specification and in the claims section thatfollows, the term “A is electrically downstream to B” relates to anelectrical component A which receives, as input, an electrical signalprovided by an electrical component B, either directly or via additionalelectrical components located electrically between electrical componentsB and A.

As used herein in the specification and in the claims section thatfollows, the term “portable” relates to a device which can be ported, ormoved around, while in its operative mode using an on-board powersupply, to a distance greater than 10 meters and/or for a duration of atleast 5 minutes, at least 10 minutes, at least 15 minutes, or at least30 minutes, without requiring a wired or wireless connection to a powersource or to a communication module such as a Wi-Fi transceiver.

As used herein in the specification and in the claims section thatfollows, the term “instrumentally induced pain” relates to any pain ordiscomfort caused by operation of the device or instrument on or in thebody of the user to provide treatment thereto.

As used herein in the specification and in the claims section thatfollows, the terms “physiological pain” and “physiologically inducedpain” relate to pain caused by the physiology of the user, irrespectiveof the presence or operation of a device or instrument on or in the bodyof the user.

It will be appreciated that certain features of the invention, whichare, for clarity, described in the context of separate embodiments, mayalso be provided in combination in a single embodiment. Conversely,various features of the invention, which are, for brevity, described inthe context of a single embodiment, may also be provided separately orin any suitable sub-combination. Similarly, the content of a claimdepending from one or more particular claims may generally depend fromthe other, unspecified claims, or be combined with the content thereof,absent any specific, manifest incompatibility therebetween.

As used herein, unless otherwise stated, the terms “substantially” and“about”, when modifying a condition or relationship characteristic of afeature or features of an embodiment of the present technology, are tobe understood to mean that the condition or characteristic is defined towithin tolerances that are acceptable for operation of the embodimentfor an application for which it is intended.

Although the invention has been described in conjunction with specificembodiments thereof, it is evident that many alternatives, modificationsand variations will be apparent to those skilled in the art.Accordingly, it is intended to embrace all such alternatives,modifications and variations that fall within the spirit and broad scopeof the appended claims.

What is claimed is:
 1. A non-invasive device for providing pain reliefto a human user, the device comprising: (a) at least two electrodesadapted to contact a surface of a body of the user; (b) a control unit;and (c) a signal generator, associated with said control unit andresponsive thereto, said signal generator and said control unit adaptedto operative connect to a power supply, said signal generator adapted,in an operative mode, to provide a series of electrical impulses to saidsurface of said body, via said electrodes, said series including aplurality of cycles, each of said cycles having a positive voltage pulseand a negative voltage pulse, wherein a frequency of said plurality ofcycles is within a range of 60-150 cycles per second, wherein atime-averaged voltage amplitude (Va_(p)) of said positive voltage pulse,over an entire duration (Tp_(positive)) thereof, is 20-90 Volts, andwherein a ramp-up section of said positive voltage pulse fulfills atleast one of the following structural conditions: (1) said positivevoltage pulse attains at least 80% of said time-averaged voltageamplitude, within a time (T80) of 70-150 nanoseconds; (2) said positivevoltage pulse increases by at least 20 Volts, within 70 nanoseconds. 2.The device of claim 1, wherein T80 is at least 75 nanoseconds.
 3. Thedevice of claim 1, wherein T80 is at least 80 nanoseconds.
 4. The deviceof any one of claims 1 to 3, wherein T80 is at most 140 nanoseconds. 5.The device of any one of claims 1 to 3, wherein T80 is at most 130nanoseconds.
 6. The device of any one of claims 1 to 3, wherein T80 isat most 120 nanoseconds.
 7. The device of any one of claims 1 to 3,wherein T80 is at most 115 nanoseconds.
 8. The device of any one ofclaims 1 to 3, wherein T80 is at most 110 nanoseconds.
 9. The device ofany one of claims 1 to 8, wherein said positive voltage pulse increasesby at least 20 Volts, within 70 nanoseconds.
 10. The device of any oneof claims 1 to 8, wherein said positive voltage pulse increases by atleast 30 Volts, within 70 nanoseconds.
 11. The device of any one ofclaims 1 to 8, wherein said positive voltage pulse increases by at least40 Volts, within 70 nanoseconds.
 12. The device of any one of claims 1to 8, wherein said positive voltage pulse increases by at least 50Volts, within 70 nanoseconds.
 13. The device of any one of claims 1 to12, wherein an intermediate time (Ti) between said positive voltagepulse and said negative voltage pulse is at least 0.1 milliseconds, atleast 0.2 milliseconds, at least 0.3 milliseconds, or at least 0.4milliseconds.
 14. The device of claim 13, wherein said intermediate time(Ti) is at most 1 millisecond, at most 0.9 milliseconds, at most 0.8milliseconds, or at most 0.7 milliseconds.
 15. The device of any one ofclaims 1 to 14, wherein said positive pulse attains at least 80% of saidtime-averaged voltage amplitude for a pulse duration within a range of70-130 microseconds, 80-120 microseconds, or 90-110 microseconds. 16.The device of any one of claims 1 to 15, wherein said positive pulse hasa substantially constant voltage amplitude for a pulse duration within arange of 70-130 microseconds, 80-120 microseconds, or 90-110microseconds.
 17. The device of any one of claims 1 to 16, wherein saidfrequency of said plurality of cycles is within a range of 70-140 cyclesper second, 80-130 cycles per second, or 80-120 cycles per second. 18.The device of any one of claims 1 to 17, wherein said negative voltagepulse is area-symmetric with respect to said positive voltage pulse,within 10 area %, within 5 area %, within 2 area %, or within 1 area %.19. The device of any one of claims 1 to 18, wherein said positivevoltage pulse attains at least 80%, at least 85%, at least 90%, at least95%, or substantially 100% of said time-averaged voltage amplitude,within 70-150 nanoseconds.
 20. The device of any one of claims 18 to 19,wherein said signal generator includes a low voltage signal generatoradapted to produce a low voltage AC signal, said low voltage signalgenerator producing a peak voltage of up to 10.0 volts up to 5.0 volts.21. The device of any one of claims 1 to 19, wherein said signalgenerator includes at least one of a voltage pre-amplifier and a voltageamplifier, adapted to amplify the voltage of a signal provided as inputthereto.
 22. The device of claim 21, wherein said voltage pre-amplifierand said voltage amplifier is disposed electrically downstream withrespect to a low voltage signal generator, and receives as input a saidlow voltage AC signal generated by said low voltage signal generator.23. The device of claim 21 or claim 22, wherein said signal generatorincludes a transformer adapted to amplify the voltage of a signalprovided as input thereto.
 24. The device of claim 23, wherein saidtransformer is disposed electrically downstream with respect to saidvoltage pre-amplifier and said voltage amplifier.
 25. The device ofclaim 22 or 23, wherein said signal generator includes an AC-to-DCconverter disposed electrically downstream relative to said transformerand adapted to produce a substantially DC signal from an input signalprovided thereto.
 26. The device of any one of claims 1 to 21, whereinsaid signal generator includes an AC-to-DC converter adapted to producea substantially DC signal.
 27. The device of claim 26, wherein saidAC-to-DC converter is disposed electrically downstream with respect tosaid voltage pre-amplifier and said voltage amplifier.
 28. The device ofany one of claims 25 to 27, wherein said AC-to-DC converter includes adiode circuit adapted to produce said substantially DC signal.
 29. Thedevice of claim 28, wherein said diode circuit includes at least onediode, and a capacitor disposed electrically downstream of said at leastone diode.
 30. The device of any one of claims 1 to 29, wherein saidsignal generator includes a switching mechanism, responsive to saidcontrol unit, adapted to transform an input signal provided to saidswitching mechanism into said series of electrical impulses.
 31. Thedevice of claim 30, wherein said switching mechanism receives as saidinput signal a substantially DC signal.
 32. The device of claim 31,wherein said switching mechanism includes a first switch, responsive tosaid control unit, adapted to generate from said substantially DC signalsaid positive voltage pulses of said series, and a second switch,responsive to said control unit, adapted to generate from saidsubstantially DC signal said negative voltage pulses of said series. 33.The device of any one of claims 1 to 32, wherein said power supplycomprises a low voltage power supply adapted to provide a nominalvoltage of at most 10 volts, at most 8.0 volts, at most 6.0 volts, atmost 5.0 volts, at most 4.0 volts, or at most 3.0 volts.
 34. The deviceof any one of claims 1 to 33, further comprising a housing enclosingsaid control unit, said signal generator, and said power supply.
 35. Thedevice of claim 34, wherein, in said operative mode, said power supplyenclosed in said housing is the sole power supply for said device. 36.The device of claim 34 or claim 35, wherein said housing has dimensionswithin the range of 4 cm×4 cm×8 mm to 6 cm×6 cm×13 mm.
 37. The device ofany one of claims 1 to 36, wherein said device has a weight in the rangeof 90 to 150 grams, excluding any power supply enclosed in said housing.38. The device of any one of claims 1 to 37, wherein said device isportable while in said operative mode.
 39. The device of any one ofclaims 1 to 38, wherein said electrodes are adapted to contact saidsurface of the body of the user at a region of the body at which pain isexperienced.
 40. A method for providing pain relief to a user, themethod comprising: (a) providing a device according to any one of claims1 to 39; (b) attaching said at least two electrodes to said surface ofthe body of the user; (c) activating said signal generator to operate insaid operative mode to provide said series of electrical impulses tosaid surface of said body, via said electrodes.
 41. The method of claim40, wherein said attaching includes attaching said at least twoelectrodes to said surface of the body at a region at which pain is feltby the user.
 42. The method of claim 41, wherein said region at whichpain is felt by the user is an abdominal area of the user.
 43. Themethod of claim 42, wherein said method is effected so as to providerelief to menstrual or pre-menstrual pains.
 44. The method of any one ofclaims 40 to 43, further comprising said user wearing said device. 45.The method of claim 44, wherein said wearing comprises attaching saiddevice to a garment worn by said user.
 46. The method of claim 44 orclaim 45, wherein said wearing comprises wearing said device while saiddevice is in said operative mode.
 47. The method of any one of claims 44to 46, wherein said device is portable, the method further comprisingsaid user moving a distance of at least ten, at least five, or at leastthree meters while wearing said device, in said operative mode, for atleast 10, at least 5, or at least 3 minutes.
 48. A non-invasive devicefor providing pain relief to a human user, the device comprising: (a) atleast two electrodes adapted to contact a surface of a body of the user;(b) a control unit; and (c) a signal generator, associated with saidcontrol unit and responsive thereto, said signal generator and saidcontrol unit adapted to operative connect to a power supply, said signalgenerator adapted, in an operative mode, to provide a series ofelectrical impulses to said surface of said body, via said electrodes,said series including a plurality of cycles, each of said cycles havinga positive voltage pulse and a negative voltage pulse, wherein afrequency of said plurality of cycles is within a range of 60-150 cyclesper second, wherein a time-averaged voltage amplitude (Va_(p)) of saidpositive voltage pulse, over an entire duration (Tp_(positive)) thereof,is 20-90 Volts, wherein a ramp-up section of a said positive voltagepulse of cycles in a first subset of said plurality of cycles has afirst ramp up time, a ramp-up section of a said positive voltage pulseof cycles in a second subset of said plurality of cycles, following saidfirst subset, has a second ramp up time, shorter than said first ramp uptime, and a ramp-up section of a said positive voltage pulse of cyclesin a third subset of said plurality of cycles, following said secondsubset, has a third ramp up time, shorter than said second ramp up time,and wherein said ramp-up section of said positive voltage pulse of saidcycles in said third subset fulfills at least one of the followingstructural conditions: (1) said positive voltage pulse attains at least80% of said time-averaged voltage amplitude, within a time (T80) of70-150 nanoseconds; (2) said positive voltage pulse increases by atleast 20 Volts, within 70 nanoseconds.